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  • 1.
    Adamczyk, Krzysztof
    et al.
    Department of Materials Science and Engineering, Trondheim, Norway.
    Søndenå, Rune
    Department for Solar Energy, IFE, Kjeller, Norway.
    Stokkan, Gaute
    Sintef Materials and Chemistry, Trondheim, Norway.
    Looney, Erin
    Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
    Jensen, Mallory
    Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
    Lai, Barry
    Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, USA.
    Rinio, Markus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Di Sabatino, Marisa
    Department of Materials Science and Engineering, NTNU, A. Getz vei 2B, NO-7491 Trondheim, Norway.
    Recombination activity of grain boundaries in high-performance multicrystalline Si during solar cell processing2018In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 5, p. 1-6, article id 055705Article in journal (Refereed)
    Abstract [en]

    In this work, we applied internal quantum efficiency mapping to study the recombination activity of grain boundaries in High Performance Multicrystalline Silicon under different processing conditions. Wafers were divided into groups and underwent different thermal processing, consisting of phosphorus diffusion gettering and surface passivation with hydrogen rich layers. After these thermal treatments, wafers were processed into heterojunction with intrinsic thin layer solar cells. Light Beam Induced Current and Electron Backscatter Diffraction were applied to analyse the influence of thermal treatment during standard solar cell processing on different types of grain boundaries. The results show that after cell processing, most random-angle grain boundaries in the material are well passivated, but small-angle grain boundaries are not well passivated. Special cases of coincidence site lattice grain boundaries with high recombination activity are also found. Based on micro-X-ray fluorescence measurements, a change in the contamination level is suggested as the reason behind their increased activity.

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  • 2.
    Adamczyk, Krzysztof
    et al.
    Department of Materials Science and Engineering, Trondheim, Norway.
    Søndenå, Rune
    Department for Solar Energy, IFE, Kjeller, Norway.
    You, Chang Chuan
    Department for Solar Energy, IFE, Kjeller, Norway.
    Stokkan, Gaute
    Sintef Materials and Chemistry, Trondheim, Norway.
    Lindroos, Jeanette
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Rinio, Markus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Di Sabatino, Marisa
    Department of Materials Science and Engineering, Trondheim, Norway.
    Recombination Strength of Dislocations in High-Performance Multicrystalline/Quasi-Mono Hybrid Wafers During Solar Cell Processing2018In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 2, article id 1700493Article in journal (Refereed)
    Abstract [en]

    Wafers from a hybrid silicon ingot seeded in part for High Performance Multicrystalline, in part for a quasi-mono structure, are studied in terms of the effect of gettering and hydrogenation on their final Internal Quantum Efficiency.The wafers are thermally processed in different groups – gettered and hydrogenated. Afterwards, a low temperature heterojunction with intrinsic thin layer cell process is applied to minimize the impact of temperature. Such procedure made it possible to study the effect of different processing steps on dislocation clusters in the material using the Light Beam Induced Current technique with a high spatial resolution. The dislocation densities are measuredusing automatic image recognition on polished and etched samples. The dislocation recombination strengths are obtained by a correlation of the IQE with the dislocation density according to the Donolato model. Different clusters are compared after different process steps. The results show that for the middle of the ingot, the gettering step can increase the recombination strength of dislocations by one order of magnitude. A subsequent passivation with layers containing hydrogen can lead to a decrease in the recombination strength to levels lower than in ungettered samples.

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  • 3.
    Andersson, Ole
    et al.
    Dept. of Physics, Stockholm University, Sweden.
    Bengtsson, Ingemar
    Dept. of Physics, Stockholm University, Sweden.
    Ericsson, Marie
    Uppsala universitet, Kvantkemi.
    Sjöqvist, Erik
    Uppsala universitet, Institutionen för fysik och astronomi.
    Geometric phases for mixed states of the Kitaev chain2016In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 374, no 2069, article id 20150231Article in journal (Refereed)
    Abstract [en]

    The Berry phase has found applications in building topological order parameters for certain condensed matter systems. The question whether some geometric phase for mixed states can serve the same purpose has been raised, and proposals are on the table. We analyze the intricate behaviour of Uhlmann’s geometric phase in the Kitaev chain at finite temperature, and then argue that it captures quite different physics from that intended. We also analyze the behaviour of a geometric phase introduced in the context of interferometry. For the Kitaev chain, this phase closely mirrors that of the Berry phase, and we argue that it merits further investigation. 

  • 4.
    Andersson, Stig
    et al.
    Göteborgs Universitet.
    Svensson, Krister
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Excitation and desorption of physisorbed H2 via the 2Σu electron scattering resonance.2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, p. 114703-1-114703-11, article id 114703Article in journal (Refereed)
    Abstract [en]

    Our high-resolution electron energy-loss measurements concern physisorbed H2 and comprise dif- ferential cross sections for the excitation of the internal H2 modes and the H2-surface bonding mode and their combinations and extend over the electron impact energy range of the classical low-energy H2 2Σu resonance. Comparison with corresponding data for the excitation of the internal modes of gas phase H2 reveals that strong elastic electron reflectivity from the Cu(100) substrate profoundly distorts the inelastic scattering pattern for physisorbed H2. We find that this influence can be corrected for and that the resulting peak cross sections agree with the H2 gas phase data, in accordance with theoretical predictions for the excitation of the internal H2 vibration. We have used corrected cross sections for the rotational mode spectra of physisorbed H2, HD, and D2 in a model concerning elec- tron induced desorption via rotation-translation energy conversion. These spectra include transitions from the ground state as well as excited levels of the physisorption potential well. H2 and HD can desorb from all levels while D2, for energetic reason, can only desorb from the excited levels. This model gives a satisfactory account of the observed desorption cross sections and predicts character- istic velocity distributions of the desorbing molecules. The cross section data for H2 and HD reveals that direct bound-free transitions also contribute to the electron induced desorption. 

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  • 5.
    Andronic, L.
    et al.
    Transilvania University of Braso, Romania.
    Moldarev, D.
    Institute for Energy Technology, Norway.
    Deribew, Dargie
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Karazhanov, S. Z.
    Institute for Energy Technology, Norway.
    Photocatalytic self-cleaning properties of thin films of photochromic yttrium oxyhydride2022In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 316, article id 123599Article in journal (Refereed)
    Abstract [en]

    Oxyhydride of yttrium (YHO) belongs to an emerging class of materials, with oxide and hydride anions sharingthe same sites in the lattice. Under sunlight irradiation, the material is transparent to visible light with trans-parency exceeding 85% and can absorb about 10% of sunlight. Furthermore, increasing light transmittance in thevisible light enhanced the self-cleaning properties of the coated materials, making these materials promisingcandidates for smart windows applications. However, the light-absorbing properties of the materials wereincreased with exposure time, and in the photodarkening state, they can absorb about 40% of sunlight. Kelvinprobe measurements show work function values between 2.9 and 4.2 eV for YHO, depending on the H2/Arpressure in the deposition chamber. Using the Kelvin probe, we demonstrate that the work function decreaseswith decreasing deposition pressure and hydrogen flow. Measurements under solar light reveal a decrease of workfunction by 0.2 eV followed by a slow relaxation with the light off. Moreover, the self-cleaning test shows that theoxyhydroxide thin films have excellent photocatalytic activity and total self-cleaning in 40 h.

  • 6.
    Anselmo, Ana Sofia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Dzwilewski, Andrzej
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Rysz, Jakub
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Bernasik, Andrzej
    Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Krakow 30–059, Poland.
    Budkowski, Andrzej
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Andersson, Mats R.
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Characterisation of vertical phase separation in polymer: fullerene blend films for photovoltaics by dSIMS and NEXAFS2011In: E-MRS 2011 Spring Meeting: Bilateral Energy Conference, Malden, MA: John Wiley & Sons, 2011, p. 62-63Conference paper (Refereed)
    Abstract [en]

    Morphological control and characterization of blend films is key in the development of viable polymer solar cells. Spontaneous formation of vertical compositional gradients during solution processing has been shown for polyfluorene:PCBM blends and rationalized with thermodynamic and kinetic models of nucleation and spinodal decomposition.[1, 2] The extent of vertical stratification is affected by polymer side-chain modification aimed at controlling polymer:fullerene miscibility.[3] Here we present high-resolution film morphology results for several polymer:fullerene systems as obtained from near-edge X-ray fine structure spectroscopy (NEXAFS) in partial and in total electron yield modes. Blend films were found to be polymer- enriched at the surface. Dynamic secondary ion mass spectrometry (dSIMS) and NEXAFS give compositional information at different depths, resulting in a more complete picture of the film morphology.

     

  • 7.
    Anselmo, Ana Sofia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Dzwilewski, Andrzej
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Rysz, Jakub
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Budkowski, Andrzej
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Polymer solar cells: Visualizing vertical phase separation in solution-processed films of polymer fullerene blends2012In: Proceedings of the 5th International Symposium Technologies for Polymer Electronics - TPE 12 / [ed] Hans-Klaus Roth, Klaus Heinemann, Ilmenau, Germany: Universitätsverlag Ilmenau , 2012, p. 125-128Conference paper (Refereed)
  • 8.
    Anselmo, Ana Sofia
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Dzwilewski, Andrzej
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Wang, Ergang
    Chalmers University of Technology.
    Andersson, Mats R.
    Chalmers University of Technology.
    van Stam, Jan
    Karlstad University, Faculty of Technology and Science, Department of Chemistry and Biomedical Sciences.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Molecular orientation and composition at the surface of APFO3:PCBM blend films2012In: Hybrid and Organics Photovoltaics Conference: Uppsala, Sweden, 2012 / [ed] Anders Hagfeldt, SEFIN, Castelló (Spain), 2012, p. 278-Conference paper (Refereed)
  • 9.
    Asker, Andreas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Axion Electrodynamics and Measurable Effects in Topological Insulators2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Topological insulators are materials with their electronic band structure in bulk resembling that of an ordinary insulator, but the surface states are metallic. These surface states are topologically protected, meaning that they are robust against impurities. The topological phenomena of three dimensional topological insulators can be expressed within topological field theories, predicting axion electrodynamics and the topological magnetoelectric effect. An experiment have been suggested to measure the topological phenomena. In this thesis, the underlying theory and details around the experiment are explained and more detailed derivations and expressions are provided.

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  • 10.
    Axelsson, Martin
    et al.
    Uppsala University.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Huang, Ping
    Uppsala University.
    Araujo, C. Moyses
    Karlstad University.
    Tian, Haining
    Uppsala University.
    Small Organic Molecule Based on Benzothiadiazole for Electrocatalytic Hydrogen Production2021In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 143, no 50, p. 21229-21233Article in journal (Refereed)
    Abstract [en]

    A small organic molecule 2,1,3-benzothiadiazole-4, 7-dicarbonitrile (BTDN) is assessed for electrocatalytic hydrogen evolution on glassy carbon electrode and shows a hydrogen production Faradaic efficiency of 82% in the presence of salicylic acid. The key catalytic intermediates of reduced species BTDN-. and protonated intermediates are characterized or hypothesized by using various spectroscopic methods and density functional theory (DFT)-based calculations. With the experimental and theoretical results, a catalytic mechanism of BTDN for electrocatalytic H-2 evolution is proposed.

  • 11.
    Bastianello, Alvise
    et al.
    Technical University of Munich, Germany; Institute for Advanced Study, Germany; Munich Center for Quantum Science and Technology (MCQST), Germany.
    Borla, Umberto
    Technical University of Munich, Germany; Munich Center for Quantum Science and Technology (MCQST), Germany.
    Moroz, Sergej
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Technical University of Munich, Germany; Munich Center for Quantum Science and Technology (MCQST), Germany.
    Fragmentation and Emergent Integrable Transport in the Weakly Tilted Ising Chain2022In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 128, no 19, article id 196601Article in journal (Refereed)
    Abstract [en]

    We investigate emergent quantum dynamics of the tilted Ising chain in the regime of a weak transverse field. Within the leading order perturbation theory, the Hilbert space is fragmented into exponentially many decoupled sectors. We find that the sector made of isolated magnons is integrable with dynamics being governed by a constrained version of the XXZ spin Hamiltonian. As a consequence, when initiated in this sector, the Ising chain exhibits ballistic transport on unexpectedly long timescales. We quantitatively describe its rich phenomenology employing exact integrable techniques such as generalized hydrodynamics. Finally, we initiate studies of integrability-breaking magnon clusters whose leading-order transport is activated by scattering with surrounding isolated magnons.

  • 12.
    Bekaert, Xavier
    et al.
    Université François Rabelais, FRA.
    Meunier, Elisa
    Institut für Theoretische Physik, DEU.
    Moroz, Sergej
    University of Washington, USA.
    Symmetries and currents of the ideal and unitary Fermi gases2012In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 2, article id 113Article in journal (Refereed)
    Abstract [en]

    The maximal algebra of symmetries of the free single-particle Schrodinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schrodinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O(N) model, a putative bulk dual of the unitary and the ideal Fermi gases is briefly discussed.

  • 13.
    Bertoni, M. I.
    et al.
    Massachusetts Institute of Technology, Cambridge, USA .
    Fenning, D. P.
    Massachusetts Institute of Technology, Cambridge, USA .
    Rinio, Markus
    Fraunhofer ISE, Laboratory and Servicecenter, Auf der Reihe 2, Gelsenkirchen, Germany .
    Rose, V.
    USA.
    Holt, M.
    USA.
    Maser, J.
    USA.
    Buonassisi, Tonio
    USA.
    Nanoprobe X-ray fluorescence characterization of defects in large-area solar cells2011In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 4, p. 4252-4257Article in journal (Refereed)
    Abstract [en]

    The performance of centimeter-sized energy devices is regulated by inhomogeneously distributednanoscale defects. To improve device efficiency and reduce cost, accurate characterization of thesenanoscale defects is necessary. However, the multiscale nature of this problem presentsa characterization challenge, as non-destructive techniques often specialize in a single decade of lengthscales, and have difficulty probing non-destructively beneath the surface of materials with sub-micronspatial resolution. Herein, we push the resolution limits of synchrotron-based nanoprobe X-rayfluorescence mapping to 80 nm, to investigate a recombination-active intragranular defect in industrialsolar cells. Our nano-XRF measurements distinguish fundamental differences between benign anddeleterious dislocations in solar cell devices: we observe recombination-active dislocations to containa high degree of nanoscale iron and copper decoration, while recombination-inactive dislocationsappear clean. Statistically meaningful high-resolution measurements establish a connection betweencommercially relevant materials and previous fundamental studies on intentionally contaminatedmodel defect structures, pointing the way towards optimization of the industrial solar cell process.Moreover, this study presents a hierarchical characterization approach that can be broadly extended toother nanodefect-limited energy systems with the advent of high-resolution X-ray imaging beamlines

  • 14.
    Björström Svanström, Cecilia M.
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Rysz, Jakub
    Institute of Physics, Jagiellonian University, Poland.
    Bernasik, Andrzej
    Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Poland.
    Budkowski, Andrzej
    Institute of Physics, Jagiellonian University, Poland.
    Zhang, Fengling
    nic Electronic (COE), Linköping University, Sweden.
    Inganäs, Olle
    IFM and Center of Organic Electronic (COE), Linköping University, Sweden.
    Andersson, Mats R.
    Department of Chemical and Biological Engineering, Chalmers University of Technology.
    Magnusson, Kjell
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Benson-Smith, Jessica
    Department of Physics, Imperial College, London, U.K..
    Nelson, Jenny
    Department of Physics, Imperial College, London, U.K..
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Device performance of APFO-3/PCBM solar cells with controlled morphology2009In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 21, no 43, p. 4398-4403Article in journal (Refereed)
    Abstract [en]

    Polymer/fullerene solar cells with three different device structures: A) diffuse bilayer, B) spontaneously formed multilayer, and C) vertically homogenous thin films, are fabricated. The photocurrent/voltage performance is compared and it is found that the self-stratified structure (B) yields the highest energy conversion efficiency.

  • 15.
    Blazinic, Vanja
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Ericsson, Leif
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Muntean, Stela Andrea
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Photo-degradation in air of spin-coated PC60BM and PC70BM films2018In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 241, p. 26-30Article in journal (Refereed)
    Abstract [en]

    The fullerene derivatives PC60BM and PC70BM are widely used as electron accepting components in the active layer of polymer solar cells. Here we compare their photochemical stability by exposing thin films of PC60BM and PC70BM to simulated sunlight in ambient air for up to 47 h, and study changes in their UV–vis and FT-IR spectra. We quantify the photo-degradation by tracking the development of oxidation products in the transmission FT-IR spectra. Results indicate that PC60BM photodegrades faster than PC70BM. The rate of photo-oxidation of the thin films is dependent on the rate of oxygen diffusion in to the film and on the photo-oxidation rate of a single molecule. Both factors are dependent on the nature of the fullerene cage. The faster photo-oxidation of PC60BM than of PC70BM is in agreement with its slightly lower density and its higher reactivity. The use of PC70BM in solar cells is advantageous not only because of its absorption spectrum, but also because of its higher stability.

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  • 16. Borchert, Dietmar
    et al.
    Brammer, T.
    Voigt, O.
    Stiebig, H.
    Gronbach, A.
    Rinio, Markus
    Kenanoglu, A.
    Willeke, G.
    Nositschka, A.
    Kurz, H.
    Large area (N) A-Si:H/(P) C-Si heterojunction solar cells with low temperature screen printed contacts2004Conference paper (Other academic)
  • 17. Borchert, Dietmar
    et al.
    Gronbach, Andreas
    Rinio, Markus
    Zippel, Elmar
    Process steps for the production of large area (n) a-Si:H/(p) C-Si heterojunction solar cells2005Conference paper (Other academic)
  • 18. Borchert, Dietmar
    et al.
    Gronbach, Andreas
    Schaefer, B.
    Rinio, Markus
    Abusnina, Mohammed
    Kenanoglu, Ali
    Willeke, Gerhard
    Large area RF deposition of thin films for silicon solar cells2004Conference paper (Other academic)
  • 19. Borchert, Dietmar
    et al.
    Hanke, Martin
    Ban, Q.
    Schmidt, K.
    Rinio, M.
    Microcrystalline silicon films as active layers in crystalline silicon solar cells2006Conference paper (Other academic)
  • 20.
    Borchert, Dietmar
    et al.
    Fraunhofer ISE, Laboratory and Servicecenter Gelsenkirchen,.
    Rinio, Markus
    Fraunhofer ISE, Laboratory and Servicecenter Gelsenkirchen,.
    Interaction between process technology and material quality during the processing of multicrystalline silicon solar cells2009In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 20, no 1, p. 487-492Article in journal (Refereed)
    Abstract [en]

    Multicrystalline silicon is the most used materialfor the production of silicon solar cells. The quality of the asgrown material depends on the quality of the feedstock andthe crystallization process. Bulk impurities, crystal defectslike dislocations and of course the grain boundaries determinethe material quality and thus the solar cell conversionefficiency. Therefore minority carrier lifetime measurementsare often done to characterize the material quality. Butthe measured values are from limited use because it is knownthat the solar cell process itself can dramatically change theminority carrier lifetime and the solar cell efficiency. In orderto obtain more detailed information of the behaviour ofdifferent defect types additionally high-resolution LBIC(light beam induced current)-measurements have been done.Since LBIC needs a pn-junction for photocurrent generationthe LBIC technique has been combined with the a-Si/c-Siheterojunction cell process, which makes it possible tomanufacture solar cells even from as cut wafers withoutchanging the material quality. With this combination ofmeasurement and preparation techniques it was possible toanalyze the influence of the diffusion process and the firingprocess on the behaviour of the three different defect types: grain boundaries, dislocation networks and bulk impurities.

  • 21. Borchert, Dietmar
    et al.
    Rinio, Markus
    Tölle, R.
    Janßen, Lars
    Nositschka, W. A.
    Kurz, H.
    Silicon nitride for backside passivation of multicrystalline solar cells2005Conference paper (Other academic)
  • 22.
    Borla, Umberto
    et al.
    Die Technische Universität München, DEU; Munich Center for Quantum Science and Technology (MCQST), DEU.
    Jeevanesan, Bhilahari
    Die Technische Universität München, DEU; Munich Center for Quantum Science and Technology (MCQST), DEU.
    Pollmann, Frank
    Die Technische Universität München, DEU; Munich Center for Quantum Science and Technology (MCQST), DEU.
    Moroz, Sergej
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Die Technische Universität München, DEU.
    Quantum phases of two-dimensional Z(2) gauge theory coupled to single-component fermion matter2022In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 7, article id 075132Article in journal (Refereed)
    Abstract [en]

    We investigate the rich quantum phase diagram of Wegner's theory of discrete Ising gauge fields interacting with U (1) symmetric single-component fermion matter hopping on a two-dimensional square lattice. In particular limits, the model reduces to (i) pure Z(2) even and odd gauge theories, (ii) free fermions in a static background of deconfined Z(2) gauge fields, and (iii) the kinetic Rokhsar-Kivelson quantum dimer model at a generic dimer filling. We develop a local transformation that maps the lattice gauge theory onto a model of Z(2) gauge-invariant spin 1/2 degrees of freedom. Using the mapping, we perform numerical density matrix renormalization group calculations that corroborate our understanding of the limits identified above. Moreover, in the absence of the magnetic plaquette term, we reveal signatures of topologically ordered Dirac semimetal and staggered Mott insulator phases at half filling. At strong coupling, the lattice gauge theory displays fracton phenomenology with isolated fermions being completely frozen and dimers exhibiting restricted mobility. In that limit, we predict that in the ground state, dimers form compact clusters, whose hopping is suppressed exponentially in their size. We determine the band structure of the smallest clusters numerically using exact diagonalization. The rich phenomenology discussed in this paper can be probed in analog and digital quantum simulators of discrete gauge theories and in Kitaev spin-orbital liquids.

  • 23.
    Boulfrad, Yacine
    et al.
    Aalto University.
    Lindroos, Jeanette
    Aalto University.
    Inglese, Alessandro
    Aalto University.
    Yli-Koski, Marko
    Aalto University.
    Savin, Hele
    Aalto University.
    Reduction of Light-induced Degradation of Boron-doped Solar-grade Czochralski Silicon by Corona Charging2013In: Energy Procedia, ISSN 1876-6102, Vol. 38, p. 531-535Article in journal (Refereed)
    Abstract [en]

    Abstract This study aims at the reduction of light-induced degradation of boron-doped solar-grade Czochralski silicon wafers by corona charging. The method consists of deposition of negative charges on both surface sides of wafer and keeping the wafer in dark for 24 hours to allow the diffusion of positively-charged interstitial copper towards the surfaces. This method proves to be useful to reduce or eliminate light-induced degradation caused by copper. The degradation was significantly reduced in both intentionally (copper-contaminated) and “clean” samples. The amount of the negative charge was found to be proportional to the reduction strength

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  • 24.
    Boulfrad, Yacine
    et al.
    Department of Micro and Nanosciences, Aalto University, Finland.
    Lindroos, Jeanette
    Department of Micro- and Nanosciences, Aalto University, Finland.
    Wagner, Matthias
    SolarWorld Innovations GmbH, Germany.
    Wolny, Franziska
    SolarWorld Innovations GmbH, Germany.
    Yli-Koski, Marko
    Department of Micro and Nanosciences, Aalto University, Finland.
    Savin, Hele
    Department of Micro and Nanosciences, Aalto University, Finland.
    Experimental evidence on removing copper and light-induced degradation from silicon by negative charge2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 18, article id 182108Article in journal (Refereed)
  • 25. Breitenstein, Otwin
    et al.
    Langenkamp, Martin
    McIntosh, K. R.
    Honsberg, C. B.
    Rinio, Markus
    Localization of shunts across the floating junction of DSBC solar cells by lock–in thermography2001Conference paper (Other academic)
  • 26.
    Brumboiu, Iulia Emilia
    et al.
    KTH; Uppsala University.
    Ericsson, Leif
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Blazinic, Vanja
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Hansson, Rickard
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Opitz, Andreas
    Humboldt-Universität zu Berlin, DEU.
    Brena, Barbara
    Uppsala Universitet.
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    The Photooxidation of PC60BM: new Insights from Spectroscopy2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, no 42, p. 25753-25766Article in journal (Refereed)
    Abstract [en]

    In the quest towards more durable solution-processed solar cells, the stability of the active layer materials under operation conditions is important. While lifetimes of several years have been demonstrated for encapsulated organic solar cells, it is generally known that degradation events can be accounted for by air components (O2 and/or water vapour) leaking into the cell through a non-ideal sealing. Here we present a fundamental study of intentional photo-degradation of the electron-acceptor PC60BM ([6,6]-phenyl-C61-butyric acid methyl ester) in air, with the purpose of improving the understanding of the electronic effects of fullerene photo-oxidation. We have studied spincoated thin films of PC60BM by X-ray Photoelectron Spectroscopy, Near-edge X-ray Absorption Fine Structure spectroscopy, and Fourier Transform Infrared Spectroscopy, before and after exposing them to simulated sunlight in air. The changes observed in the spectra obtained by these complementary methods were compared with calculated spectra of a large set of possible oxidation products of PC60BM where oxygen atoms have been attached to the C60 cage. The best fit with experimental IR spectra of photodegraded PC60BM films was obtained for a linear combination of calculated spectra for two degradation products, a dicarbonyl and an anhydride, both with open cages with 58 carbon atoms, and the pristine PC60BM molecule. From this comparison, we conclude that the conjugation of the fullerene cage is disturbed by the formation of several carbonyl-based derivatives on the C60 cage, accompanied by a transition from sp2 to sp3-hybridized carbon. The π* resonance in the C1s NEXAFS spectrum was found to be a very sensitive probe for small changes to the fullerene cage, and FT-IR was needed in combination with O1s NEXAFS, to identify the oxidation products.

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  • 27.
    Brumboiu, Iulia Emilia
    et al.
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    Ericsson, Leif K.E.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Hansson, Rickard
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Moons, Ellen
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Eriksson, Olle
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    Brena, Barbara
    Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala, Sweden.
    The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C60 derivative PCBM2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, p. 054306-Article in journal (Refereed)
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  • 28.
    Budkowski, Andrzej
    et al.
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Bernasik, Andrzej
    Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Krakow 30–059, Poland.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Lekka, M
    The Henryk Niewodnicza¶nski Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow, Poland.
    Zemla, J
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Jaczewska, Justyna
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Haberko, Jakub
    Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Krakow 30–059, Poland.
    Raczkowska, Joanna
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Rysz, Jakub
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Awsiuk, K
    M. Smoluchowski Institute of Physics and Research Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM) Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
    Structures in multi-component polymer films: their formation, observation and applications in electronics and biotechnology2009In: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Proceedings of the XLII Zakopane School of Physics, Zakopane 2008, Vol. 115, no 2, p. 435-440Article in journal (Refereed)
    Abstract [en]

    Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches are based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it o®ers a one-step process to deposit and align simultaneously domains, rich in di®erent polymers, forming various device elements: (i) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors. (ii) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color). (iii) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries. (iv) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles

  • 29.
    Budkowski, Andrzej
    et al.
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Zemla, Joanna
    Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Awsiuk, Kamil
    Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland.
    Rysz, Jakub
    M. Smoluchowski Insitute of Physics, Jagiellonian University, Reymonta 4, Krakow 30–059, Poland.
    Bernasik, Andrzej
    Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Krakow 30–059, Poland.
    Björström Svanström, Cecilia M.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Lekka, Małgorzata
    Niewodniczanski Institute of Nuclear Physics, Polish Academy of Science, Krakow, Poland.
    Jaczewska, Justyna
    Institute of Physics, Jagiellonian University, Krakow, Poland.
    Polymer Blends Spin-Cast into Films with Complementary Elements for Electronics and Biotechnology2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Special Issue: Contributions from the 4th International Conference on Polymer Behavior (IUPAC), Lodz, Poland, September 19–23, 2010, Vol. 125, no 6, p. 4275-4284Article in journal (Refereed)
    Abstract [en]

    Versatility of solution-processing strategy based on the simultaneous rather than additive deposition of different functional molecules is discussed. It is shown that spin-cast polymer blends result in films with domains that could form elements with complementary functions of (i) solar cells, (ii) electronic circuitries, and (iii) test plates for protein micro-arrays: Alternating layers, rich in electrondonating polyfluorene and electron-accepting fullerene derivative, result in optimized solar power conversion. Surface patterns, made by soft lithography, align conductive paths of conjugated poly(3-alkylthiophene) in dielectric polystyrene. Proteins, preserving their biologically activity, are adsorbed to hydrophobic domains of polystyrene in hydrophilic matrix of poly(ethylene oxide). The authors report the research progress on structure formation in three polymer blend families, resulting in films with complementary elements for electronics and biotechnology. Blend film structures are determined with secondary ion mass spectrometry, atomic force microscopy, and fluorescence microscopy. In addition, the authors present recent results on (i) structure formation in fullerene derivative/poly(3-alkylthiophene) blends intended for solar cells, (ii) 3-dimensional SIMS imaging of conductive paths of poly(3-alkylthiophene) in dielectric polystyrene, (iii) test lates for multiprotein micro-arrays fabricated with blend films of hydrophobic polystyrene and thermoresponsive poly (N-sopropylacrylamide).

  • 30.
    Carvalho, Rodrigo P.
    et al.
    Uppsala Universitet.
    Alhanash, Mirna
    Uppsala Universitet; Chalmers tekniska högskola.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Brandell, Daniel
    Uppsala universitet.
    Araujo, C. Moyses
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala universitet.
    Exploring Metastable Phases During Lithiation of Organic Battery Electrode Materials2022In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, no 2, article id e202200354Article in journal (Refereed)
    Abstract [en]

    In this work, the Li-ion insertion mechanism in organic electrode materials is investigated through the lens of atomic-scale models based on first-principles theory. Starting with a structural analysis, the interplay of density functional theory with evolutionary and potential-mapping algorithms is used to resolve the crystal structure of the different (de)lithiated phases. These methods elucidate different lithiation reaction pathways and help to explore the formation of metastable phases and predict one- or multi-electron reactions, which are still poorly understood for organic intercalation electrodes. The cathode material dilithium 2,5-oxyterephthalate (operating at 2.6 V vs. Li/Li+) is investigated in depth as a case study, owing to its rich redox chemistry. When compared with recent experimental results, it is demonstrated that metastable phases with peculiar ring-ring molecular interactions are more likely to be controlling the redox reactions thermodynamics and consequently the battery voltage.

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  • 31.
    Carvalho, Rodrigo P.
    et al.
    Uppsala University.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Brandell, Daniel
    Uppsala University.
    Araujo, Moyses
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Artificial intelligence driven in-silico discovery of novel organic lithium-ion battery cathodes2022In: Energy Storage Materials, ISSN 2405-8289, E-ISSN 2405-8297, Vol. 44, p. 313-325Article in journal (Refereed)
    Abstract [en]

    Organic electrode materials (OEMs) combine key sustainability and versatility properties with the potential to enable the realisation of the next generation of truly green battery technologies. However, for OEMs to become a competitive alternative, challenging issues related to energy density, rate capability and cycling stability need to be overcome. In this work, we have developed and applied an alternative yet systematic methodology to accelerate the discovery of suitable cathode-active OEMs by interplaying artificial intelligence (AI) and quantum mechanics. This AI-kernel has allowed a high-throughput screening of a huge library of organic molecules, leading to the discovery of 459 novel promising OEMs with candidates offering the potential to achieve theoretical energy densities superior to 1000 W h kg(1). Moreover, the machinery accurately identified common molecular functionalities that lead to such higher-voltage electrodes and pointed out an interesting donor-accepter-like effect that may drive the future design of cathode-active OEMs.

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  • 32.
    Carvalho, Rodrigo P.
    et al.
    Uppsala University.
    Marchiori, Cleber F. N.
    Uppsala University.
    Oltean, Viorica-Alina
    Uppsala University.
    Renault, Steven
    University Nantes, FRA.
    Willhammar, Tom
    Stockholm University.
    Gomez, Cesar Pay
    Uppsala University.
    Araujo, Moyses
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Brandell, Daniel
    Uppsala University.
    Structure-property relationships in organic battery anode materials: exploring redox reactions in crystalline Na- and Li-benzene diacrylate using combined crystallography and density functional theory calculations2021In: Materials Advances, E-ISSN 2633-5409, Vol. 2, no 3, p. 1024-1034Article in journal (Refereed)
    Abstract [en]

    Organic-based materials are potential candidates for a new generation of sustainable and environmentally friendly battery technologies, but insights into the structural, kinetic and thermodynamic properties of how these compounds lithiate or sodiate are currently missing. In this regard, benzenediacrylates (BDAs) are here investigated for application as low-potential electrodes in Na-ion and Li-ion batteries. Aided by a joint effort of theoretical and experimental frameworks, we unveil the structural, electronic and electrochemical properties of the Na(2)BDA and Li(2)BDA compounds. The crystal structure of these systems in their different sodiated and lithiated phases have been predicted by an evolutionary algorithm interplayed with density functional theory calculations. Due to difficulties in obtaining useful single crystals for the BDA salts, other methods have been explored in combination with the computational approach. While the predicted structure of the pristine Na(2)BDA compound has been experimentally confirmed through the 3D Electron Diffraction (3DED) technique, the hydrated version of Li(2)BDA is analysed through single crystal X-ray diffraction. The calculated cell voltages for the sodiation (0.63 V vs. Na/Na+) and lithiation (1.12 V vs. Li/Li+) processes display excellent quantitative agreement with experimental findings. These results validate the developed theoretical methodology. Moreover, fundamental aspects of the electronic structures and their relationship with the reaction thermodynamics are discussed. The results suggest a possible disproportionation between the sodiated phases of Na(2)BDA, supporting a two-electron process, and also unveil major differences for the two employed cations: Na+ and Li+.

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  • 33.
    Castellanos, Sergio
    et al.
    Massachusetts Institute of Technology, Massachusetts, USA.
    Kivambe, Maulid
    Massachusetts Institute of Technology, Massachusetts, USA.
    Hofstetter, Jasmin
    Massachusetts Institute of Technology, Massachusetts, USA.
    Rinio, Markus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Lai, Barry
    Argonne Photon Source, Illinois, USA.
    Buonassisi, Tonio
    Massachusetts Institute of Technology, Massachusetts, USA.
    Variation of dislocation etch-pit geometry: An indicator of bulk microstructure and recombination activity in multicrystalline silicon2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 18, p. 1-7, article id 183511Article in journal (Refereed)
    Abstract [en]

    Dislocation clusters in multicrystalline silicon limit solar cell performance by decreasing minoritycarrier diffusion length. Studies have shown that the recombination strength of dislocation clusterscan vary by up to two orders of magnitude, even within the same wafer. In this contribution, wecombine a surface-analysis approach with bulk characterization techniques to explore theunderlying root cause of variations in recombination strength among different clusters. We observethat dislocation clusters with higher recombination strength consist of dislocations with a largervariation of line vector, correlated with a higher degree of variation in dislocation etch-pit shapes(ellipticities). Conversely, dislocation clusters exhibiting the lowest recombination strength containmostly dislocations with identical line vectors, resulting in very similar etch-pit shapes. Thedisorder of dislocation line vector in high-recombination clusters appears to be correlated withimpurity decoration, possibly the cause of the enhanced recombination activity. Based on ourobservations, we conclude that the relative recombination activity of different dislocation clustersin the device may be predicted via an optical inspection of the distribution and shape variation ofdislocation etch pits in the as-grown wafer.

  • 34.
    Chavhan, Sudam D.
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Abellon, Ruben D.
    Dept. of Chemical Engineering, Technische Universiteit Delft, The Netherlands.
    Savenije, Tom J.
    Dept. of Chemical Enginering, Technische Universiteit Delft, The Netherlands.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Photovoltaic Study of p-type NiO/PC70BM Hybrid Solar Cells2011Conference paper (Refereed)
    Abstract [en]

    Generally, hybrid solar cells are fabricated by using electron donating conducting polymers or molecules and electron accepting inorganic material e.g. metal oxide nanoparticles, such as TiO2, ZnO or SnO2. Inorganic metal oxides posses interesting physical properties like high electron mobility, transparency in the visible spectrum and high dielectric constant. However, there are very few reports on hybrid solar cells fabricated with p-type metal oxide and n-type organic molecules. We have studied photovoltaic properties of bilayer hybrid solar cells constituted of p-type NiO and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) molecule. The thin films of NiO were prepared on fluorine doped SnO2 (FTO) substrates by RF sputtering in Ar/O2 mixture atmosphere. To fabricate hybrid solar cells, a PC70BM solution was spin coated on top of the smooth and uniform layer of NiO, having thickness of 90 nm. Current-voltage characteristics were measured in dark and under illumination with monochromatic light of wavelength 460 nm and an incident illumination power of 9 mW/cm2. A short circuit current density of 0.15 mA/cm2, open circuit voltage of 0.23 V, and fill factor of 0.26 were found. To understand the photovoltaic mechanism of this type of hybrid solar cells we studied also the bulk heterojunctions made up of p-type NiO nanoparticles with different PCBM molecules.

  • 35.
    Chavhan, Sudam D.
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Solution Processed NiO Hole Transporting Layer in P3HT:PCBM Bulk Heterojunction Organic Solar Cells2011Conference paper (Refereed)
    Abstract [en]

    Despite of low fabrication cost and flexibility, limited life time is the major disadvantage of bulk heterojunction organic solar cells (OSCs). The main causes of short life time of OSCs is the degradation of active layer in presence of light and O2 and the effect of the acidic PEDOT:PSS on the ITO electrode. To overcome this problem PEDOT: PSS can be replaced by a p-type metal oxide hole transportation layer, such as NiO. There are reports on vacuum deposited NiO hole transporting layers in OSCs. Here, we have used the low-cost spin coating technique to deposit the NiO layer from a dispersion of NiO particles in methanol. Concentration and deposition parameters were optimized to obtain 40-50 nm thick layer of NiO as observed by tapping mode atomic force microscopy. The device performance of P3HT:PCBM solar cell with ITO/PEDOT: PSS and ITO/NiO electrodes was compared.

  • 36.
    Chuan Chen, Max
    et al.
    KTH.
    Omanakuttan, Giriprasanth
    KTH.
    Hansson, Rickard
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Strömberg, Axel
    KTH.
    Hallén, Anders
    KTH.
    Rinio, Markus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Lourdudoss, Sebastian
    KTH.
    Sun, Yan-Ting
    KTH.
    Low temperature activation of B implantation of Si subcell fabrication in III-V/Si tandem solar cells2019In: Proceedings of the 36th EU PVSEC 2019, WIP, 2019, p. 764-768Conference paper (Other academic)
    Abstract [en]

    In this work, we investigated the Si pre-amorphization implantation (PAI) assisted low temperatureannealing process to activate boron implantation in n-Si in a hydride vapor phase epitaxy (HVPE) reactor, which canbe used for the Si subcell fabrication in the III-V/Si tandem solar cells enabled by the corrugated epitaxial lateralovergrowth (CELOG). A uniform boron activation in Si and a low emitter sheet resistance of 77 /sq was obtained atannealing temperatures of 600-700°C. High-resolution x-ray diffraction was used to study the recrystallization ofamorphous silicon and the incorporation of boron dopants in Si. Hall measurements revealed p-type carrierconcentrations in the order of 1020 cm-3. The n-Si wafers with B implantation activated at 700°C by HVPE wereprocessed to solar cells and characterized by the standard light-current-voltage measurement under AM1.5 spectrumand external quantum efficiency measurements. The developed B implantation and low temperature activationprocesses are applied to the InP/Si seed template preparation for CELOG, on which CELOG GaInP over a Si subcellwith a direct heterojunction was demonstrated.

  • 37.
    Cirillo, E.N.M.
    et al.
    Univ Roma La Sapienza, Dipartimento Sci Base & Applicate Ingn, Rome, Italy.
    Krehel, O.
    Eindhoven Univ Technol, Inst Complex Mol Syst, Eindhoven, Netherlands.
    Muntean, Adrian
    Eindhoven Univ Technol, Inst Complex Mol Syst.
    van Santen, R.
    Eindhoven Univ Technol, Inst Complex Mol Syst, Eindhoven, Netherlands.
    Sengar, A.
    Indian Inst Technol Delhi, Delhi, India.
    Residence time estimates for asymmetric simple exclusion dynamics on strips2015In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 442, p. 436-457Article in journal (Refereed)
  • 38.
    Colangeli, M.
    et al.
    Univ Laquila, Italy.
    Muntean, Adrian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Reduced Markovian descriptions of Brownian dynamics: Toward an exact theory2022In: Frontiers in Physics, E-ISSN 2296-424X, Vol. 10, article id 903030Article in journal (Refereed)
    Abstract [en]

    We outline a reduction scheme for a class of Brownian dynamics which leads to meaningful corrections to the Smoluchowski equation in the overdamped regime. The mobility coefficient of the reduced dynamics is obtained by exploiting the Dynamic Invariance principle, whereas the diffusion coefficient fulfils the Fluctuation-Dissipation theorem. Explicit calculations are carried out in the case of a harmonically bound particle. A quantitative pointwise representation of the reduction error is also provided and connections to both the Maximum Entropy method and the linear response theory are highlighted. Our study paves the way to the development of reduction procedures applicable to a wider class of diffusion processes.

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  • 39.
    Damas, Giane B.
    et al.
    Uppsala University; Linköping University.
    Costa, Luciano T.
    Fluminense Federal University, Brazil.
    Ahuja, Rajeev
    Uppsala University.
    Araujo, Moyses
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Uppsala University.
    Understanding carbon dioxide capture on metal-organic frameworks from first-principles theory: The case of MIL-53(X), with X = Fe3+, Al3+, and Cu2+2021In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 155, no 2, article id 024701Article in journal (Refereed)
    Abstract [en]

    Metal-organic frameworks (MOFs) constitute a class of three-dimensional porous materials that have shown applicability for carbon dioxide capture at low pressures, which is particularly advantageous in dealing with the well-known environmental problem related to the carbon dioxide emissions into the atmosphere. In this work, the effect of changing the metallic center in the inorganic counterpart of MIL-53 (X), where X = Fe3+, Al3+, and Cu2+, has been assessed over the ability of the porous material to adsorb carbon dioxide by means of first-principles theory. In general, the non-spin polarized computational method has led to adsorption energies in fair agreement with the experimental outcomes, where the carbon dioxide stabilizes at the pore center through long-range interactions via oxygen atoms with the axial hydroxyl groups in the inorganic counterpart. However, spin-polarization effects in connection with the Hubbard corrections, on Fe 3d and Cu 3d states, were needed to properly describe the metal orbital occupancy in the open-shell systems (Fe- and Cu-based MOFs). This methodology gave rise to a coherent high-spin configuration, with five unpaired electrons, for Fe atoms leading to a better agreement with the experimental results. Within the GGA+U level of theory, the binding energy for the Cu-based MOF is found to be E-b = -35.85 kJ/mol, which is within the desirable values for gas capture applications. Moreover, it has been verified that the adsorption energetics is dominated by the gas-framework and internal weak interactions.

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  • 40.
    Das, Aritra
    et al.
    Indian Institute of Science, IND; University of Maryland, USA.
    Borla, Umberto
    Technische Universität München, DEU; Munich Center for Quantum Science and Technology (MCQST), DEU.
    Moroz, Sergej
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013). Technische Universität München, DEU; Munich Center for Quantum Science and Technology (MCQST), DEU; KTH Royal Institute of Technology; Stockholm University,.
    Fractionalized holes in one-dimensional Z2 gauge theory coupled to fermion matter: Deconfined dynamics and emergent integrability2023In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 6, article id 064302Article in journal (Refereed)
    Abstract [en]

    We investigate the interplay of quantum one-dimensional discrete Z2 gauge fields and fermion matter near full filling in terms of deconfined fractionalized hole excitations that constitute mobile domain walls between vacua that break spontaneously translation symmetry. In the limit of strong string tension, we uncover emergent integrable correlated hopping dynamics of holes which is complementary to the constrained XXZ description in terms of bosonic dimers. We analyze numerically quantum dynamics of spreading of an isolated hole together with the associated time evolution of entanglement and provide analytical understanding of its salient features. We also study the model enriched with a short-range interaction and clarify the nature of the resulting ground state at low filling of holes and identify deconfined hole excitations near the hole filling νh = 1/3.

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  • 41.
    de Araujo, L. O.
    et al.
    Federal University of Technology, BRA.
    Neto, A. L.
    Federal University of Technology, BRA.
    Scalon, L.
    University of Campinas, Campinas, BRA.
    Rodrigues, P. C.
    Federal University of Technology, BRA.
    Floriano, J. B.
    Federal University of Technology, BRA.
    Araujo, C. M.
    Uppsala University.
    Marchiori, Cleber
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Barreto, R. C.
    Federal University of Technology, BRA.
    A new CBD-CC-E spectral similarity scale for optimizing computer-simulated UV–vis spectra2021In: Computational and Theoretical Chemistry, ISSN 2210-271X, E-ISSN 2210-2728, Vol. 1197, article id 113116Article in journal (Refereed)
    Abstract [en]

    A new CBD-CC-E spectral similarity scale is proposed to optimize computer-simulated UV–vis spectra. The scale was tested using the S1←S0 spectrum of the dithienyl-diketopyrrolopyrrole molecule (DPP2T), an important building block for manufacturing materials for optoelectronic applications. Our results indicate that the spectrum calculated at M06/6-311++G(d,p) level was the one that best reproduced the intensity and shape features of the experimental spectrum, while CAM-B3LYP/6-311++G(d,p) was the one that best reproduced the energy. The CBD-CC-E scale makes the comparison between computer-simulated and experimental spectra statistically based, allowing a systematic and automated choice of the theory level whose calculated spectrum best reproduces the shape, intensity or energy of the experimental UV–vis spectrum.

  • 42.
    De Nardis, Luca
    et al.
    Sapienza Univ Rome, Italy.
    Caso, Giuseppe
    Ericsson Res, Kista, Sweden.
    Alay, Ozgu
    Univ Oslo, Norway.
    Ali, Usman
    Sapienza Univ Rome, Italy.
    Neri, Marco
    Rohde&Schwarz, Italy.
    Brunström, Anna
    Karlstad University, Faculty of Economic Sciences, Communication and IT (discontinued), Centre for HumanIT. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).
    Di Benedetto, Maria-Gabriella
    Sapienza Univ Rome, Italy.
    Positioning by fingerprinting with multiple cells in NB-IoT networks2022In: / [ed] Nurmi, J; Lohan, ES; Sospedra, JT; Kuusniemi, H ; Ometov, A, Institute of Electrical and Electronics Engineers (IEEE), 2022Conference paper (Refereed)
    Abstract [en]

    Narrowband Internet of Things (NB-IoT) has quickly become a leading technology in the deployment of IoT systems and services, thanks to its appealing features in terms of coverage and energy efficiency, as well as compatibility with existing mobile networks. Increasingly, IoT services and applications require location information to be paired with data collected by devices; NB-IoT still lacks, however, reliable positioning methods. Time-based techniques inherited from Long Term Evolution (LTE) are not yet widely available in existing networks, and are expected to perform poorly on NB-IoT signals due to their narrow bandwidth. This investigation proposes a set of strategies for NB-IoT positioning, based on fingerprinting, that use coverage and radio information from multiple cells. The proposed strategies are evaluated on a large-scale dataset that includes experimental data from two NB-IoT operators. Results show that the proposed strategies, using a combination of coverage and radio information from multiple cells, outperform current state-of-the-art approaches based on single cell finger-printing, with a minimum average positioning error of about 20 meters, consistent across different network scenarios, vs. about 70 meters for current state-of-the-art. 

  • 43.
    Dzwilewski, Andrzej
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Anselmo, Ana Sofia
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    The effect of light exposure on P3HT:PCBM films: a NEXAFS study2011Conference paper (Refereed)
    Abstract [en]

    A simple photolithography method was developed for patterning organic field effect transistors (OFETs) prepared from blends of poly(3-hexylthiophene), P3HT, and [6,6]-phenyl-C61-butyric acid methyl ester, PCBM.(1) This Photo-induced and Resist-free Imprint patterning (PRI) technique allows also the single solution step production of organic CMOS circuits.(2) It consists of two subsequent processing steps: 1) exposure: photo-irradiation of the P3HT:PCBM blend by visible laser light and 2) development: rinsing of the film in an organic solvent mixture that is selective for PCBM. As a result, two electronically different materials are obtained, i.e. the exposed and developed (ED) material, and the unexposed and developed (UD) material. The method is based on the modification of the PCBM component in the irradiated area, which becomes effectively insoluble in the solvent mixture, while the PCBM in the non-irradiated area is removed during development. Therefore, we expect that the UD material is pure P3HT, a hypothesis that is confirmed by the p-type conductivity of the ED region. Near-Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS) was used to determine the surface composition of these films. C K-edge NEXAFS spectra of pristine, photo-exposed, and developed blend films, as well as films of the pure components were measured at the synchrotron facility MAX-lab in Lund, Sweden. The spectra for P3HT and PCBM are significantly different and the components can be clearly distinguished in the blend spectra. From the relative intensities of the P3HT and PCBM peaks, the actual blend composition can be estimated, both on the surface, using partial electron yield (PEY), and deeper in the sub-surface region of the film, using total electron yield (TEY). From the similarity of the spectra of the UD blend sample and the pure P3HT sample, we conclude that the remaining material after washing the pristine blend is indeed P3HT, and the ED blend sample retains its two-component character. The surface composition of the blend films is significantly more polymer-rich than the bulk blend ratio used to prepare the film. Both for the pristine blend and the photo-exposed blend differences are observed between the PEY and TEY spectra, indicating the existence of a polymer-enriched surface. Such gradients in thin films of P3HT:PCBM blends have been observed by others using variable-angle spectroscopic ellipsometry,(3) NEXAFS,(4) and neutron reflectometry,(5) and also in other polymer:PCBM blends by dynamic secondary ion mass spectrometry (d-SIMS).(6)

    References (1) Dzwilewski, A.; Wagberg, T.; Edman, L. J. Am. Chem.Soc. 2009, 131, 4006. (2) Dzwilewski, A.; Matyba, P.; Edman, L. J. Phys. Chem. B 2010, 114, 135. (3) Campoy-Quiles, M., et al., Nature Materials 2008, 7,158-164 (4) Germack,D.S. et al., Appl. Phys. Lett. 2009, 94, 233303. (5) Kiel, J.W. et al., Soft Matter 2010, 6, 641-646. (6) Björström, C.M. et al, J. Phys.: Condens. Matter 2005, 17, L529-L534.

  • 44.
    Dzwilewski, Andrzej
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Anselmo, Ana Sofia
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Light induced effects in PCBM:P3HT blend films2012In: Hybrid and Organics Photovoltaics Conference: Uppsala, Sweden, 2012 / [ed] Anders Hagfeldt, SEFIN, Castelló (Spain), 2012, p. 155-155Conference paper (Refereed)
  • 45.
    Dzwilewski, Andrzej
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Anselmo, Ana Sofia
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    Svensson, Krister
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Zharnikov, Michael
    Moons, Ellen
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Technology and Science, Materials Science.
    X-ray absorption study of light induced effects in PCBM:P3HT blend films2011In: Photovoltaics at the nanoscale: Hasselt University (Belgium) 24-28 October 2011, Hasselt University, Belgium, 2011, p. 59-59Conference paper (Refereed)
  • 46. Díaz-Herrera, B.
    et al.
    Montesdeoca-Santana, Amada
    Jiménez-Rodriguez, E.
    González-Díaz, B.
    Hernández Rodríguez, C.
    Guerrero-Lemus, Ricardo
    Rinio, Markus
    Borchert, Dietmar
    Upgraded metallurgical grade silicon for solar cell fabrication2009Conference paper (Other academic)
  • 47.
    Edvardsson, Elisabet
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Band structures of topological crystalline insulators2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Topological insulators and topological crystalline insulators are materials that have a bulk band structure that is gapped, but that also have toplogically protected non-gapped surface states. This implies that the bulk is insulating, but that the material can conduct electricity on some of its surfaces. The robustness of these surface states is a consequence of time-reversal symmetry, possibly in combination with invariance under other symmetries, like that of the crystal itself. In this thesis we review some of the basic theory for such materials. In particular we discuss how topological invariants can be derived for some specific systems. We then move on to do band structure calculations using the tight-binding method, with the aim to see the topologically protected surface states in a topological crystalline insulator. These calculations require the diagonalization of block tridiagonal matrices. We finish the thesis by studying the properties of such matrices in more detail and derive some results regarding the distribution and convergence of their eigenvalues.

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  • 48.
    Ekblom, Filip
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Z2-Gauge Theory with Matter: Dispersive behaviour of a dimer in a 1+1-dimensional lattice2023Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The intention with this thesis is to investigate a dimer in a spin chain. Inorder to do that, a model from Z2-gauge theory is taken as the theoretical motivation to construct a discrete lattice with Ising spin properties. A dimer is then allowed to exist indirectly in the empty space between sites. We choose to tackle the problem through a quantum mechanical approach in 1+1-dimensions, distancing ourselves from the original description in quantum field theory. The exposition begins by reviewing the spatial construction of the entire chain as well as its components, and ends with a discussion of time development where the main concern is dispersion in addition to reflection against a static charge.

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  • 49.
    Ekhagen, Sebastian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Silicon solar cells: basics of simulation and modelling: Using the mathematical program Maple to simulate and model a silicon solar cell2017Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    The main goal of this thesis was to simulate a solar cell with the symbolic manipulation tool Maple and discuss the strength and weaknesses of using Maple instead of the already known simulation program PC1D. This was done mainly by solving the three essential differential equations governing the current density and excess electron and hole densities in the solar cell. This could be done easily by using known simplifications especially the low injection assumption. However it was also a success without using this particular simplification but the solutions had to be achieved using a numerical method instead of direct methods. The results were confirmed by setting up the same solar cell with PC1D. The conclusion is that Maple gives the user increased freedom when setting up the solar cell, however PC1D is easier to use if this freedom is not needed. At the end of this thesis a brief introduction is also made on the possibility of using Maple with a tandem cell setup instead of single junction.

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  • 50.
    Emanuelsson, Christian
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Electronic Structure and Film Morphology Studies of PTCDI on Metal/Semiconductor Surfaces2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organic semiconductors have received increasing attention over the last decades as potential alternatives for inorganic semiconductors. The properties of these films are highly dependent on their structural order. Of special interest is the interface between the film and its substrate, since the structure of the interface and the first few layers decide the growth of the rest of the film. The interface structure is determined by the substrate/molecule interactions, the intermolecular interactions and the growth conditions.

    In this thesis, thin films of the organic semiconductor PTCDI have been studied using complementary microscopy and spectroscopy techniques on two metal-induced surface reconstructions, Ag/Si(111)-√3×√3 and Sn/Si(111)-2√3×2√3. These surfaces were chosen because they have different reactivities and surface periodicities. On the weakly interacting Ag-terminated surface, the film growth is mainly governed by the intermolecular interactions. This leads to well-ordered films that grow layer-by-layer. The interaction with the substrate is through electron charge transfer to the molecules from the substrate. This results in two different types of molecules with different electronic structure, which are identified using both STM images and PES spectra. On the more strongly interacting Sn-terminated surface the molecules adsorb in specific adsorption geometries and form 1D rows. At around 0.5 ML coverage the rows also interact with each other and form a 4√3×2√3 reconstruction and beyond one ML coverage the growth is characterized as island growth. The interaction with the substrate is mainly due to heavy electron charge transfer from the Sn atoms in the substrate to the C atoms in the imide group, but also the N atoms and the perylene core in PTCDI are involved. In these systems, the interactions with the surfaces result in new states inside the HOMO-LUMO gap, and the intermolecular interactions are dominated by O···H and O···H-N hydrogen bondings.

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